Super duper MPG 318 (part 2)

OK lets have some discussion, I been slowly gathering parts for the 92 dakota 318 auto truck and the time for much improved MPG is here, I have an a-500 to swap in place of the 518 and am preparing some heads to throw my suite of mods at but really wish I could get more compression while still keeping the flat tops.

Cylinder head mods are going to be opening the intake valve seat to match the size of the valve as the seat diameter is much smaller, then run as sharp of valve seat angles as I can get on the intake while mirror polishing the ex valve to reject heat. I have found nice gains just opening the port at the PR pinch especially on the PR side because the fuel sprays there instead of the back of the valve and opening it up allows more to hit the valve where it belongs. Also I will be running ferd yellow 4 hole infectors. Top it all off with about .030 head milling and I just might try the "singh grooves" this time.

I will zero deck the block again as I have done in the past and run a .028 head gasket but I still am only going to have just under 11 to 1... I would really like to try at least 12 to 1 and retard the cam timing to bleed off some of the compression and let the cylinder pressure work on the crank a little longer before opening the ex valve. I really don't want a dome screwing up the flame front... maybe I should build some heat stoves to suck hot air off the exhaust manifolds?

When I did this basic engine in a 1/2 ton it would not ping with nearly 11 to 1 on 87 octane, it actually seemed more octane tolerant than it did stock. It gained some MPG from that but really wanted to try more compression but could not easily figure that out... that truck benefited from slowing down the RPM by installing 265-65-20 tires (stock had 245-75-16 tires and 3.55 gears) . Recently I was going to put some 2.76s in this dakota that also has 3.55s but much shorter 235-75-15 tires but when I pulled the gears out of storage they were rusted beyond usable... I am looking for another nice 2.76 or maybe 2.94 for the 8.25.

I will not make the bed unusable so no tonneau cover. I will not switch wheels and tires as I drive on dirt roads and can't have rubberband tires getting holes in them and bending wheels.

I have thought about finding some slightly smaller injectors and unplugging the O2 to make it run leaner but I know that could be a crapshoot. I read once upon a time about a wideband A/F sensor someone sells that will send a false o2 signal signal to the computer to change the ratio to whatever you set it at, anyone know who sold such a thing? How would that work if I wanted run 16 to 1 or something at cruise but normal A/F 12.5 or so ratio at WOT?

Anything else I am missing (besides EGR, still not buying that)?

You know, I was reading your super mileage 273 thread earlier today.

Since your 92 is OBD1 you might consider replacing the stock computer with a megasquirt unit. Then you can control the AF ratio, timing, etc to your hearts content.

How hard that would be, I do not know.

Unfortunately for me I can grasp physical/mechanical stuff pretty well but I really struggle with electronics, megasquirt hurts my head just reading about people trying to get it working.

I would really like a TBI holley style injection and eddy RPM intake to give the fuel longer to evaporate but that would be tough learning curve for an old brain.

Might want to upgrade to 96+ sequential injection, More efficient and you can get "caned tunes" for it.

Perhaps it should be a Super-Duper 273 ?

The dual sparkplugs of a 5.7 V8 are such an advantage that engine should be the starting point.

(Since even the late dual sparkplug 4.7 have bad reputations I will not consider those.)

An air to fuel ratio of more than 20, perhaps even 25
can gain a lot,
and you “probably” need fuel injection to keep all 8 cylinders even.

Dodge Ram, or maybe Dodge Magnum station wagon?

Better aero of Magnum would help a lot.

Couple things as I have actually driven and modded a 1992 ext cab long bed dakota for mileage. Combo was 5.2 518 8 1/4 with 3.55 gears.

I did not do internal engine mods though.

A vinyl roll up soft tonneau cover picked up over 1/2 mpg on the interstate.

Electric fan setup was worth a little.

31"x 10.5x 15 tires helped trim rpms and upped fuel mileage. Better choices than those for mileage purposes out there though.

Mopar performance midlength headers and y pipe with a magnaflow muffler.

Used the yellow Ford injectors as well.

I could knock down 20mpg at 75 to 80mph on I 20 between Atlanta and Birmingham. Made the trip at least once per week for over a year.

As far as compression is it the lack of valve cutouts in the piston tops or the shallowness of the combustion chamber that is limiting you? KB167 would help with the former.

KB piston would also help bump the compression a little with the higher top ring land.

The magnum head chamber is very efficient when set up with quench and doesn't need the help of a dual plug deal like the hemi chamber does to get a complete burn.

I have the Dakota, use it a lot, it won't sell for much here (2wd) and it would be much harder to set engines and things in the bed when I go to the junk yard, machine shop and such...

I do have an eagle 5.7 I could swap some early 5.7 pistons in for a big compression bump, they are slightly taller and have a bigger dome that should not interfere with flame travel...I would love to have a hemi in it, I just think it would be a much bigger project than I want to do. It would require me to build motor mounts (don't know how) build headers maybe/probably (don't know how) building a wiring harness (could do it but I hate electrical) then I got to figure out how to get tach to work, CEL, kickdown...

I would also think a 273 would be better suited to this project but again I would have to build motor mounts and a crank sensor mount, buy a block, run a flat tappet cam or spend a pile on retro roller lifters if they are even currently available or run a flat tappet (not the end of the world) compression would be even harder to increase...

The question of compression limit in the 318 magnum is when you mill the heads much more than .030 you will end up with the valve poking below the surface and after about .060 you are gonna start getting too close to the seat it's elf. Also poking it below the surface means valve notches in the pistons witch gives the fuel and air a small place to hide from burning quickly. If I do this I will notch my stock pistons only as much as I absolutely have to for valve clearance, the valve notch in the kb167 (I ran them in the first MPG 318) is huge, nice for a big cam but will negate the compression I am after by milling it so much in the first place. I suppose I could turn the diameter of the valve down to match the seat instead of opening the seat to the valve... then I could probably safely mill them to .060, anyone know what size the chamber would be on a magnum if milled .060? Assuming I can get it down to 58 CC and .028 quench would only give me about 11 to 1 witch is pretty good in a normal build but I really want it very high so I can retard the cam to bleed pressure and take advantage of a dramatically increased expansion ratio.

What about improving the transmission? Roller bearings instead of thrust washers? Better torque converter? Have you given thought to a custom ground cam?

Missed part one someplace...maybe this stuff was covered in part one...maybe not.

Anyway, look at what manufacturers are doing today to improve MPG. Fuel injection is obvious, the 92 Dak should have it. Leave the O2 sensor, let the computer control the fuel, it will do a better job of controlling fuel use at all RPM ranges than you could do. Low tension piston rings. Look at any gen3 hemi or LS engine with over 100K, you can sometimes still see cross hatch in the cylinders. That's low ring tension and fuel injection with no fuel wash. Look at eliminating other friction in the engine; roller cam/lifters/rockers. Let the engine breathe, nice big cold air intake. Free flowing exhaust includes headers.

You mention not looking at tires. While you don't want/need rubber band tires, you do need an smooth, even tread pattern, the big, knobby, mudder tires will kill MPG. With the trans, A-500 with lock-up converter and a reasonable rear gear ratio. Might have a lot of takers on that 518 trans you're taking out...might fund other things.

Think about driving habits. Using AC is better than having windows down. Using no AC and windows up is best. Trim the fat on the truck, low weight will help the cause. Fiberglass hood, bumpers, remove the tailgate for a net. Try to trim 200-400lbs from the truck. Funny how some of the MPG improvements are also things done on a race car.

Anybody see the video on youtube where the guy put a lawn lower carb on a 302/4 speed Maverick, he got 40+ mpg.

I saw that lawn mower carb 302, it is basically acting like a governor to keep from making any power (burning fuel). I also thought about something like that and how it could maybe tolerate a very high compression ratio based on the fact it is never filling the cylinders so it won't build as much cylinder pressure, then it could reap the benefits of a very high expansion ratio.

Are the aluminum Magnum Mopar Performance sold cylinder heads too rare to find?

Seems like I remember Larry Shepard writing they were “about” 52 cc combustion chambers and the deck could be milled a lot.

Didn’t Ebogger find some aluminum MP Magnum cyl heads for the Magnum 5.9 V8 he transplanted into a v6 Dakota?

Long ago we had a Mopars thread about whether aluminum heads
affected either max hp or max bsfc,
my reading of what reliable data there was led to concluding no measurable differences.

Mazda’s 14 to 1 engine used aluminum heads.

On a 5.2 Magnum I would stay below 12.7 static cr

Are there any production 4” inch steel pistons out there for industrial engines,
like natural gas or 2 stroke heavy bunker oil?

I toyed with this idea for a long time maybe using a flattop LS1 Piston with probably an maybe an offset ground crank and 2" rod journals and the Late 302 heads and a ported SP2P (dual plane with isolated near equal length runners) intake with a tremec. Small tube shorty headers and a single 3" exhaust with a flowmaster Y pipe. Late model roller block probably a reground stock cam for more lift.

With the right gear in a semi aerodynamic car like a late 80's Chrysler Conquest (easy v8 swap my buddy has one) I was going to shoot for easy 30's on the highway. Build a broad torque curve with decent power and high manifold vacuum at cruise speed for efficient burn.

I had a 94 Firehawk LT1 that ran in the 13's stock and would cruise on the highway at 70 MPH barely ticking over 1700 RPM and 31 MPG.

https://bringatrailer.com/listing/1980-volkswagen-rabbit/

Took my drivers test in one of these. On any serious hill it struggled to do 30-45mph. The engine had so much blow by dad ran a hose to the rear bumper to keep the oil from undercoating the car. People didn't tailgait for long... they passed or dropped back. That thing worn out got 40mpg. Lawnmower carb Maverick and diesel rabbit would be compelling drag race. Car and Driver says the VW 0-60 was 21.3sec with a 22.2sec 1/4 mile.

Our family had one of those and my youngest brother made 800 mile round trips in “Smokey”
to mining school in Rolla, MO
routinely getting high 30s and low 40s MPG.

That is also the VW diesel engine that the EPA lab in Research Triangle Park NC
converted to spark ignition and ran on methanol without changing the compression ratio,
as described in their very educational late 1990s scientific paper.
Diesel cycle and Otto cycle energy efficiency was within 1% of each other.

That's very interesting. If you have any links to those tests I'd love to read them. Thank you

Yes I would love to find a pair of the aluminum magnums or eddelbrocks or heck even one of the iron EQ, R/T, RHS... to use as they all have a much larger pushrod pinch that keeps the fuel injector from spraying on the side of the port. I can't find my old notes but I do seem to remember they all had smaller chambers than the stock head, even the chinese crap has a smaller chamber but even worse PR pinch. I just can't find any and when I do find them they are very expensive.

This tread got me thinking about my 65 Sat with the 273. This might be a fuel efficient car to drive. Think so? Can any aluminum intake fit this engine (with a little work)? I have an SP2P thing.

Not a 273 expert but if I recall correctly the intake bolt angle is different on those somehow. The sp2p could likely be made to work enlarging or slotting the bolt holes on the intake though.

Is the car currently running? If so what kind of mileage are you getting now?

Yes I think this could be a good car for highway fuel mileage depending upon the rest of the combo. 25mpg should be within reach with possibly slightly more.

I have an sp2p for the 440 I am building for my RV. I'll be doing some testing with it along with a stock 440 thermoquad intake, stock 413 intake with 450 holley, and possibly a performer 440 with a thermoquad. When you only get 6-8 mpg even just a small increase can make a big difference.

the 64-66 273 has a slightly different intake bolt pattern, close enough you can wallow out the holes and make it work, on the other hand an SP2P ain't gonna make any noticeable difference in MPG, that's the reason few were made and sold. The area of the curve where it helps is such a low RPM you would need an even lower stall speed converter than stock or a manual and highish gear that can keep it at low RPM cuz even a 2.76 with no OD is spinning pretty good at 75 MPH without some very tall tires. If I had a 273 and was running a carb for MPG set up I would run a stock 318 dual plane intake and pre emissions carter BBD carb.

Did you do any testing with an sp2p with your previous combo?

hard to find since they moved it to epa archive

https://archive.epa.gov/otaq/technology/web/pdf/sae-2002-01-2743-v2.pdf

sample quote

The unique EPA engine used for this work is a turbocharged, PFI spark-ignited 1.9L, 4-cylinder engine with 19.5:1 compression ratio. The engine operates unthrottled using stoichiometric fueling from full power to near idle conditions, using exhaust gas recirculation (EGR) and intake manifold pressure to modulate engine load. As a result, the engine, operating on methanol fuel, demonstrates better than 40% brake thermal efficiency from 6.5 to 15 bar BMEP at speeds ranging from 1200 to 3500 rpm, while achieving low steady state emissions using conventional aftertreatment strategies. Similar emissions levels were realized with ethanol fuel, but with slightly higher BSFC due to reduced spark authority at this compression ratio.

end quote

What rings to use should be given serious thought.

Newest rings reduce friction.

I have read that just one compression ring, and one oil control ring, is not out of the question if max efficiency is the main goal.

LD4B performer, RPM, and even m1 single plane none of em made a hoot of difference, maybe 1 MPG from best to worst and I doubt the SP2P would be any better without a corresponding drop in RPM. I think the important action is in the heads where it gets mixed the most and burned. I am a firm believer that as the TQ range of the manifold (and entire combo) goes down the overall combo would improve by matching the TQ curve by reducing RPM of the engine at cruise speeds either by gearing with OD, LU or higher rear gear ratio, the reason I came up with that theory is because of the zero deck tight quench 318 magnum I ran in a 98 ram 1500 ex cab long bed, tight quench and high compression gave me a little bit improved MPG and TQ but when I switched from a 245-75-16 tire to a much taller 275-65-20 tire it really got good MPG and loafed along at 80 with very low RPM (I think it barely did 2000 RPM at 80MPH), doing 70 it would easily do 20 mpg, that's what makes me think I could do better in a much smaller dakota by running a really high rear gear to keep the RPM down along with building the engine to make more TQ down real low.

Zero decking my current block, running .028 head gaskets with a 2.94 gear almost don't even feel like an experiment to me at this point, I would almost bet on 22 MPG in this little truck. That's why I am really want to push the compression and gearing in this thing.

If anyone knows where I can get some aftermarket heads (not chinese) for a magnum that don't cost an arm and a leg please let me know.

I agree with the lower cruise rpm and it is the way the manufacturers have gone to help mileage with 1700-1800 cruise rpm on the highway .

Wouldn't whatever intake makes the best torque at cruise rpm be the one to help fuel mileage the most?

Didn't you run 302 heads on the first build? Maybe those ports were the limiting factor in the intakes not making much difference?

As far as the heads go could you just tube the push rod holes in the magnum heads and cut them open instead of spending a bunch on aftermarket stuff? Would moving the location/ angle of the injector boss work?

Just thinking out loud not trying to argue. I appreciate you sharing your experience with us.

The cuda engine I did use 302 heads, I used to subscribe to the theory that the smallest port made the most MPG because of velocity and such, I think all that did was hurt performance with no MPG improvement. I think the 920 head with 1.88 intake valves and a little porting would have been best for that engine, I think they are the best SB head for MPG unless you could really slow down your RPM.

The stock magnum head has no tube, just raw casting between port and pushrod. The EQ is made like this also but does have a slightly wider PR pinch. The Eddy, RHS, mopar aluminum and iron R/T all have a drilled PR tube but they also already have a much larger PR pinch, tubing them and opening it would really give a nice shot at the back of the valve I am just having a real hard time finding any much less a pair I can afford. The cheap chinese ones on fleabay have no tube and an even smaller pinch than stock heads, looking at the picture of jegs and others magnum replacements it looks like they are all selling the cheap chinese junk named as their own.

Awesome! thanks

Not a mopar but my 99 Corvette got 26-27 mpg. 6 speed and was turning 1300 @ 70. RPM does make a difference

back in the early 70's, i had a 64 barracuda with a 273 2bbl and a pushbutton 904. it had an open 7 1/4 rear, but i don't remember the gear in it.
running back and forth to work on the interstate at 65-70 [this was during the 55 mph speed limit time] that thing got around 26mpg.
was a really sweet running car until my old man clipped a phone pole............

I know it's mentioned in here, and obv you've got some LA knowledge too, but I read all your posts in the Gen III section and think this is where you should be:

https://www.holley.com/products/eng...dge_dakota_gen_iii_hemi_swap_components/

My curiosity is getting to me. Back in the old days, when cars were cars and gas was gas, I had several 318 powered vehicles that would regularly pull 20-25 mpg on the highway. Gas isn't what it used to be. What kind of gas mileage are you expecting to get out of this super duper 318, and what is its expected cost to get that mpg? The port injected 96 318 in my 4x4 truck is only getting 10 mpg around town. and around 13 on the highway.

I agree with the above,
but would add that
- ignition timing is not what it used to be
- air to fuel ratio is not what it used to be

NOx pollution requirements have hurt fuel economy in a large way
Low fuel economy has pumped a lot of carbon dioxide into the air.
Low fuel economy have emptied a lot of money from wallets.
The money could have been spent on reducing water pollution, setting aside wilderness areas, etc

It keeps getting worse, NOx pollution equipment wise.

I telephoned my brother 2 days ago and asked if he had a minute.
He replied: I have an hour and 21 minutes
because I am sitting outside the KW dealership in Memphis waiting for the service department to open
because the check engine light is coming on and off on this new &#@ vacuum truck
and I know from experience I do not want it to go into de-rate.

Agree, my 01 360 van at best gets 14 maybe 15 going 70. The 69 Rt Charger 440 got 17 and I never.. put my foot thru the carb!

https://en.wikipedia.org/wiki/Shell_Eco-marathon

I certainly did not expect it,
but while playing for my 92 year mother
old black and white tv episodes of the Lawrence Welk Show from 1955-1964,
there are frequent Dodge commercials,
and some of those commercials say something like
“a totally stock Dodge model abc got xy mpg in the latest Shell Fuel Economy Marathon competition.”

Ethanol is the main culprit in the loss of fuel mileage. It is just a filler and a scam. Had a Honda Civic that would get 37mpg with mostly interstate driving. When I filled with ethanol free gas, it would get 41 mpg. Same hwys repeated over 50 trips with each.

It's not the ethanol, it burns, it produces power, at 10% there is no way it can cost you 10% MPG. Yes there is slightly less energy per gallon so in the same engine you would get very slightly lower MPG. On the other hand if the engine was not compromised to run on gasoline (yes they are compromised to run on gasoline) and was instead built with much higher compression, as much as double the compression than you could extract a lot more energy from an ethanol powered engine than you can from a gasoline engine. If we had e-85 around here I would be trying to run 16 to 1 compression and get much better MPG and TQ.

Cars got better MPG 30 or 40 years ago because we had lead in the gas permitting more MPG and we drove slower, you can get much better MPG in these modern cars if you set the cruise at 50MPG and could somehow keep the stupid 8 9 10 speed automatics from downshifting all the time, more compression would give the engine more TQ and require less of those down shifts.

As far as NOX costing MPG yes it costs a lot, almost every engine ever mass produced can tolerate at least one more point of compression that is generally considered to be worth about 5% improvement in MPG, imagine if every car suddenly got 5% better MPG how much cheaper fuel could be... and many engines can easily handle 2 points compression increase, the reason they can't do this is because NOX is formed with those much higher compression ratios and right now there is not a good enough and cheap enough catalyst to get rid of the NOX in the exhaust so lower than ideal compression ratios have been the go to answer for the manufacturers along with EGR that statistically reduces the chances of a fuel molecule from finding an oxygen molecule in a timely manner.

Close but ethanol does not make the same power as gas volume for volume 15% ethanol means maybe 10% less fuel millage.

Friday May 27, 2022
letters section of the Wall Street Journal
has a letter from
Andrew Randolph, ECR Engines, Welcome, North Carolina
titled
“E15 Gasoline can save you money at the pump”

He claims that E15 has 1.5% less energy than E10 but “should” cost 6 cents per gallon than E10

Since gasoline BTU per gallon varies both regionally and seasonally
and Ethanol depends on the
price of corn,
human labor,
and financial speculation,
(all rising sharply recently)
my gut tells me there is “wiggle room” to make a case either way.

Fuel mileage with ethanol v/s non ethanol gas in my Civic was tested over a long period of time with repeatable results. Only other difference in the gas that I am aware of was ethanol free was 90 octane and ethanol gas was 87. Maybe some emissions additive in the 87 had something to do with it? Stumbled on the mileage difference after I found a station near Gadsden AL that sold the ethanol free for the same price as other stations charged for the 87 swill. It was on my regular route I drove for work through that area twice per week for over a year.

Just a heads up there is a set of 920 heads for sale on for a bodies only now. Any idea what the combustion chamber size on those is?

I have a pair of nice 920s in the attic I think the chambers were 58CC but it has been a long time and going strictly by memory on that. Maybe I could find some cheap 1.6 or 1.7 shaft rockers and a long runner MPI intake for LA heads... better yet could I buy a TBI with 8 injectors and just extend the existing wires to pulse them? I really think TBI is the best for an MPG project, the last mass produced engine sold in the USA with TBI got 50+ MPG.

TBI can be “spot on” if the intake manifold is “spot on” dividing air flow to each cylinder equally.

Since most TBI has 2 injectors or more,
that tells you it is hard to divide to each cylinder runner equally.

Having sequential multi point fuel injection SMPI seems good,
but should not each fuel injector be of slightly different flow rate to “put the icing on the cake”
since it is nearly impossible to make all intake runners flow equally?

Modern SMPI with equal flow rate injectors are said to typically be 8% off from best to worst air to fuel ratio deviation result.

Those heads on a roller/magnum tweener 318 block with the kegger and your 92 obd1 might be an interesting combo. Might help you get another 1pt of compression you mentioned you wanted depending on how much the heads could be cut.

OK so I got to thinking about this, pulled those heads from the attic and CCd them at 64 CC and can easily take .080 off before getting close to the valve, I could even throw in some old 1.88s and still mill .070. The PR pinch is wider than a magnum head and has a hole drilled for it instead of the raw casting like the magnum so it could be opened even more... from past experience I know I will have to slot the PR hole larger side to side to fit a roller cam motor (or go flat tappet) but that will not restrict the pinch width. I would just need to figure out how to drill the bolt holes for the kegger (backwards jig?)and find pushrods, rockers, 1.88s...


Just filling and eyeballing the level till it just barely covered the intake valve gives me 52 CC chambers. Plugging that into KB calculator with .030 quench gives me 12.2 compression. Maybe I can find flat valves to get a tiny bit more....

I need a math genius to double check my math but I figure I need to retard the cam timing about 20 degrees to keep cylinder pressure similar to the motor I ran in that 1500 ram. This would also allow the exhaust another 20 degree push on the crank. This is the cam specs I found for the 92 cam, (I am gonna assume the 98 cam was close enough to the same it wouldn't really matter).

Intake valve diameter 1.925 inches
Cam design type: mild hydraulic roller
Intake valve timing:
......Lobe centerline 115.5
......Advertised duration 251 degrees
......Opens btdc 10 degrees
......Closes abdc 61
.....maximum lobe lift 0.27 inches
.....rocker arm ratio 1.6
.....gross intake valve lift 0.432
Exhaust Valve diameter 1.625 inches
.....Lobe centerline 109.5
.....Advertised duration 261
.....Opens bbdc 60 degrees
.....closes atdc 21
.....maximum ex lobe lift 0.27
.....rocker arm ratio 1.6
.....gross exhaust valve lift 0.432


Going from 10.2 compression to 12.2 compression and retarding the cam timing 20* gives me a bump from 8.3 dynamic to 8.5 dynamic if I am right.

I found a hughes 9001 cam in the attic I forgot about, can't find specs butt I think it was pretty small

1994-1995 iron V10 camshaft specs might be a clue to the best fuel economy.

In their SAE paper Chrysler engineers proudly stated that this new bigger ”towing” engine was more than 10% better BSFC than the GM 454 V8

Since there has been a clear trend from 180 on up to 207+ coolant temperatures think about experimenting there.
Since there is good older evidence that 140 - 160 is best for peak high rpm power,
those higher coolant temps were adopted to increase fuel economy at lower cruise rpms.

5.7 engine’s variable valve timing would allow “dialing in” the highest tolerable dynamic compression ratio.
A “de-stroked” 5.7 with a longer connecting rod would have “superior leverage” with a less torque robbing rod to crank angle.

I already run a 205 t-stat in all my magnum powered trucks, I can't find any higher.

The rod stroke ratio is over 1.85 in a 318, the 5.7 is just over 1.74, to match the 318 it would need about 3.35 stroke witch is too much to gain (lose?) from offset grinding and using stock bearing undersizes so then I need different rods probably a chevy 2.0 size, then custom pistons and balancing. I have a set of 6.25" 2.1" journal chevy rods (I think there are bearings to use with a 2.0 journal in these larger rods) but it would still need custom pistons balancing and the machine work to destroke it and I should probably buy a steel 6.1 crank to replace the 5.7 cast crank if turning it down that much.

Like I said I could easily build a late 5.7 with early 5.7 pistons with stuff I have laying around, it would be very easy to fine tune a tight quench (around .030) and very high compression (12.5ish) as the pistons are taller and have a larger dome and MDS would be sweet for this also so the actual engine it'self would be the easy part, the rotating mass is waaaay lighter than an old 318... I really would love to run a new hemi but man the installation kit stuff is very expensive, $900 headers, $150, motor mounts, $2000+ engine control, custom AC lines, PS lines, coolant hoses... and so far nobody has volunteered parts or money, sticking with the magnum I can re-use a ton of stuff.

HRD does the 205 thermostat help mileage or is it an emissions thing? I have always run a 180 stat as I don't like running on the edge of overheating all the time. Atlanta asphalt in the summer sitting in traffic is like an oven.

The hughes cam you found- is it a 9704? That is the current baby roller cam they offer for 318's. IIRC they started similar grinds at number 9701.

I just use it for hotter heat and a little better MPG, I don't really concern myself with emissions.

a 205 T-stat doesn't fully open until 210 or 215 degrees, so the engine will usually run a couple [?] degrees hotter sitting in traffic.
this is where a factory designed cooling fan/shroud assembly works very well keeping the temperature in check.
these days, i prefer a factory setup over any aftermarket item, although others have had success using what the aftermarket offers.
just my experience and opinion.
your mileage will vary.

I run a dual electric fan setup from a Dodge Intrepid in my B1500. OEM part from a donor. It along with the aftermarket 3 row rad do a much better job at cooling than the OEM set up ever did.

I am not interested in any chinese electrical parts though. My experience has been I am better off setting the money on fire and saving the aggravation of having to replace them again in the next month or so.

My temp barely gets to 205* on a hot day, it only actually runs a couple degrees warmer than a 195*.

I second the use of OE electric fans, those aftermarket ones barely do anything. I have found that I can run around without any fan on most rigs and never get hot as long as it don't sit and idle at the drive thru or anything.

185 thermostats have been the specified rating since at least the 40's. Nothing to do with economy, everything to do with decreased engine wear not to mention oil sludging.

In fact a well know MOPAR engine builder told me to not leave the line (with aluminum heads) till the temp was 210 degrees so to build heat into them. The difference was 3 tenths in the eight, from 160 to 210 degrees

A 180 thermostat doesn't being to open until 3 or so degrees of its rated temp- so 177. Full open temp is 15-20 degrees above the rated temp. Most engine wear happens on startup and is not because of a 180 vs 205 thermostat.

You would be wrong. Go peruse the image I attached to my prior post. Begins opening at 157-162 degrees, fully open at 183-187 degrees. Uses the same thermostat as the pre-79 v8's and the values were confirmed this last weekend with my IR gun.

The rated temperature is the fully open temperature.

You reference a paper that shows a temp for the beginning of opening at about 160 degrees, and fully opened at 180. That is a 160 stat.

IR guns are notoriously inaccurate. Not sure how you could get a temp on the thermostat itself through the housing anyway.


https://knowhow.napaonline.com/temperature-control-engine-thermostat-testing-tips-and-
tricks/#:~:text=The%20rating%20listed%20on%20the,180%2C%20so%20177%20to%20183.

"The rating listed on the thermostat is the point at which the device begins to open. This is not the full open temperature, which is typically 15-20 degrees above the listed temp. For example, a 180 degree thermostat begins to open within three degrees of 180, so 177 to 183."



https://www.aa1car.com/library/thermostat_diagnose_replace.htm


"Most late model thermostats are calibrated top open around 195 to 200 degrees F. The thermostat should be fully open about 20 degrees F higher than its rated temperature for maximum flow, and should maintain engine temperature in the 200 to 230 degree range."

I should not have mentioned thermostats, since replies wandered off topic from Super duper MPG.
Sorry Dave.

I wonder whether there is a retired Chrysler employee
who saved a dyno room graph that plotted
the Octane rating of pump gasoline versus the Compression Ratio of a test engine,
hopefully the 1992 Magnum 5.2 V8?

Octane could be Research, or Motor, or EPA Anti Knock Index.

Compression Ratio could be either static, or the more predictive Dynamic.

I am not sure if Willem Weertman is alive or answering questions,
but he was the chief engineer
and he cared enough to write a book.

Since we are in the “Incredible Transition” to battery electric vehicles
you would think secrecy about such cylinder head knowledge would have lessened to near nothing.

I'm not worried, I think it is all a very useful discussion sort of related to the topic. My personal thought is it helps evaporate the fuel better so it burns faster and more completely before the ex valve opens and relieves the pressure, anything burning after the ex valve open is not contributing to power or MPG. Secondly a higher temp evaporates out sludge forming moisture in the oil faster so it should help longevity, probably more of an issue on engines that get driven a lot of short trips and don't see max temp much. Also just having a thermostat in the system makes tuning easier as it holds at one certain operating temp instead of continually fluctuating based on load and outside temp and such. My heater feels a little hotter with a 205 stat and it gets cold a lot here. All things considered it is not a huge deal but they are cheap and easy to swap so a fun thing to play with.

Any idea where to get headers made for this? I have ran the numbers in several on the line calculators and seems I need primary pipes around 1" X 105" long, aiming for most TQ boost around 1500-2000 RPM. Seems like I could even run opposite firing cylinders into each other with this long of primaries.

This is the premier long tube header maker,
but the prices will widen your eyes.

https://burnsstainless.com/blogs/articles-1/not-all-tubing-is-created-equal

Before sending that level of $
perhaps fab up a “proof of concept” with thin wall aluminum electrical conduit you can bend yourself,
and try it out for a few thousand miles,
not expecting it to last beyond a MPG testing period?

I doubt even having the correct pulse arrive back at the exhaust valve seat at low rpms will improve BSFC more than a few percent.

I would spend the $ on some wind tunnel testing time,
or cheap coasting down steady grade hills.

this is what I need https://burnsstainless.com/blogs/articles-1/bundle-of-snakes-180-degree-headers-1

I don't expect it to be a huge thing by it self but combining many tricks the whole thing should be pretty cool. My main thing i if I can improve the low end TQ of the engine it can operate at a lower RPM reducing friction and giving more time for the pressure to work on the crank before being released.

I already have a great hill I do red-neck wind tunnel testing on, I figured out I can block 1/2 the grill and a few other things on the front end and pick up a few MPH at the bottom. I think I may have gotten that idea from you years ago.

My builder uses an 8 into 1 arrangement on a very successful Hydroplane Program. Obviously won't work in a conventional automotive application but if you had a mid or rear engine...

Kevin

When you say “this is what I need”
you need the Caldwell Development restricted Dodge V8 header, near the end of the article, right?

sample quote

The last photo shows a header we built for Caldwell Development for a Reynard chassis Lemans Prototype powered by a restricted Dodge V-8.

Because of the restrictor, the engine rpm was limited making it an ideal application for the 180 degree header layout.

end quote

I still have doubts,
but agree “it ain’t the craziest experiment ever funded”

Before welding metal
I would try computer modeling the torque gain of such a header in the rpm range of 1200 to 1600.

Article that shows those Caldwell Development headers... among other things.

--> Bundle of snakes article <--

HRD I think there may be a simpler path than 8ftlong primary tube headers. An anti reversion chamber in the exhaust near the end of the collector would likely give you some of the increased low end torque you are looking for without the huge expense and pain in the [censored].

Some 4/2/1 headers and longer than normal collectors may also help.



https://www.youtube.com/watch?v=HNeY_Vge5gs

Anyone know of intake and exhaust valves that will drop in a magnum head but not be concave? Flat valves would give me just a little more compression...

Do the original valves need replacement? If you need to bump compression a little bit then mill the heads or run a thinner head gasket. Seems like a lot of expense for little gain.

I see you're looking at custom built headers too. I haven't read the entire thread, but you might want to think about adapting one of the new eight speed transmissions. Expensive, but a lot to be gained from it. There are controller setups to shift it manually.

I'm trying to get ridiculously high compression while keeping a perfect flat top piston, milling the heads as much as possible (about .030), zero deck the block, .028 composite head gaskets or .010 steel shim and piston about .020 down then retard the cam to bleed off excess pressure and increase time the combustion pressure presses on the piston before opening the exhaust valve (similar to a miller cycle engine).

Since you are going all out for compression have you considered having the heads angle milled?

I had not considered it yet, my first thoughts about it are all the head bolt holes being at an angle as well as the seating surface for them, same with the intake bolts, dowl pins will be crooked... I have never done it maybe I am over thinking it???

Depends on how far you take it.

https://www.onallcylinders.com/2016...f-head-milling-to-gain-more-compression/

Sodium filled valves are bigger and would both increase static compression AND reduce pre-spark mixture temperatures.

What SRT valve sizes/stem lengths did Chrysler factory install lately?

Thermal barrier coating would also “suck up” additional CC’s

USA economy needs stimulus desperately Hot Rod Dave,
we propose your checking account sacrifice itself.......

Are they stock pistons? Stock pistons where not flat they where dished on the magnums. Similar to this...

360's are dished like that. 5.9's have a soap dish shaped dish. 5.2's are flat tops with no dish.

The sodium hemi valve stems are about .200 longer than a magnum exhaust valve. There are some older small block chevy sodium valves about the right length but 11/32 v/s 5/16 stem and 1.55 diameter. If a valve job and guides were needed they would likely work but I have not test fit one. If hardened seats were wanted or needed they would work for sure.

The 6.4 is the only one I know of with sodium ex valves and they are 1.65 VS 1.6 magnum valves butt like you mentioned just eyeballing them next to a magnum valve are about .200 longer. They are also dented in so no compression bump.

Well i got a 95 318 and it had the same style pistons as the 360, Don't know if anything changed in the previous years.

The 5.9V8 pistons withe the oval soap dish increase “tumble” ( or barrel motion )

The original flat top 5.2 pistons probably had superior squish jet effect.

Original 5.2 pistons seemed to be slightly less than 20 thousandths in the hole

5.9 pistons seem to be slightly more than 50 thousandths in the hole.

The 5.9 needed a custom cylinder head design.

Defiantly not factory pistons. From about 1972-2003 they had a flat top with no dish or valve relief from the factory.

It was all about the NOX, no other reason for the 5.9 to have that dish, a KB107 style piston and about .035 piston to head clearance would have been perfect.

“Fast Burn” does slightly decrease NOx,
so yes a “oval racetrack” shaped cavity that concentrates “Tumble”
would both reduce compression ratio, pinging,
and reduce NOx.

The original 1994 iron V10 truck engine used those same 5.9 V8 soap dish pistons “as a cost saving measure” according to Willem Wertmann.
I wonder which engine size had the lowest grams of NOx per mile ?

I suspect the 5.2 V8 has the best brake specific fuel consumption.

First year 5.7 V8 claimed “6% better BSFC”

Well it don't do me any good on this build but it looks like the 03-08 5.7 hemi 2.0" intake valve would almost drop in with a seat cut and finding a spring to fit the smaller retainer (possibly a GM 3100 V6 spring with very mild cams). It is just a tiny bit longer, maybe .020"

On this engine the larger diameter would mean less shaving of the heads and less compression, the bigger diameter, lighter valve and retainer would give me a little more power but I am after crazy compression.

It is worth being “crazy”
but only about “Dynamic Compression Ratio”
and maybe even more important
“Dynamic EXPANSION ratio”

BLM
“best lobes matter”


“Best return on Investment” MPG teaks
are still most likely to be aero and tires.

It is best to maximize compression and expansion ratios. Compression ratio is probably realistically not possible to go any higher than about 10 to 1 dynamic compression even on good premium pump fuel with the best possible fuel atomization and thermal management plan but the expansion ratio can and should be be as high as possible so my plan is to retard intake valve timing to keep under that dynamic compression and make expansion as high as I can figure out how to with a last possible degree before opening the exhaust valve. Since both valve timing events need to happen much later than stock I should be able to simply retard the stock cam and get what I am after for the most part.

As for tires I can't do much compromise on them, I need some mush for driving on dirt roads a lot.

As for aromatics I am trying to find some sort of sheet plastic I can use for blockingoff some of the grill, building belly pans and such right now, it doesn't help that I live 100 miles from a city of any sort. I would bet the biggest amounts of fixable wind drag are from underneath the truck. I might do an experiment with 10 foot of plywood running from the top rear of the cab sloped down to the rear edge of the open tailgate, this should be a very dramatic improvement but could not be left for real world use however it should let me know if there is much to gain from aero. If I did this I should be able to drive with less load witch means less engine heat produced so I can block off even more grill. I can even do this while gathering parts for the rest of it.

I think I am going to get some EQ heads but I got to finger out a time to drive 100 miles in the opposite direction I normally travel to go get em before he sells em to someone else.

https://www.youtube.com/watch?v=E0ass_AxloM

pickup aerodynamics. its an FU 150 but the idea is the same.

HRD, I am not sure if this unit would work on our obd1 trucks or not. Guess it depends on whether or not our crank sensor is inductive. It appears to be a simple way to add some cruise timing to aid the fuel mileage.

https://www.ebay.com/itm/224879329155

That's interesting for sure... I have noticed these magnum engines the timing jumps all around at idle, every one of them jumps continuously around 5 or 10 degrees just sitting idling, I wonder if it could somehow stabilize that? It shows up both with a timing light and on the scanners data stream on every one of them.

I have seen the timing jump your talking about on LA engines with worn out timing chains.

Never put a light on a magnum engine though since the computer controls it all.

I wonder if a timing chain tensioner would correct most of it?

This is by design and is how the PCM micro controls the idle RPM as the IAC can't react fast enough for minor adjustments.

Interesting.

Timing jumps around a lot at 1600 rpm level highway cruise too,
On an Actron Scantool I have seen it vary from 35 to 45 degrees btdc
when the speed in MPH seemed very steady,
but EGR was flowing

Is it something that can be tuned out of the system with a custom SCT tune?

It's not the timing chain for a couple reasons... for one when they were brand new trucks I used to watch them do this and figured it was to give them a rumbly exhaust note but I also noticed they did it at cruise on the scanner. The other bigger reason you know it is not the timing chain is it is being triggered directly off the crank shaft not any thing driven by the timing chain. I bet if you could somehow stabilize it at cruise and idle near the higher numbers you would notice an MPG increase from that. Maybe you could put a regular distributor in with about 18* idle, 35* mechanical and about 10* vacuum advance then figure out a way to trigger the cam sensor and so bypass the computer control of timing but still keep it there squirting in fuel.

That would never work. The factory ECU would pitch a fit without some kind of modification to its firmware. I would just replace the ECU altogether at that point unless you need it for transmission control.

This thing is also compensating for emissions. Replace outright or flash it if that is even an option.

Well I did some aeromatics experiments lately with it and didn't find much (although it was not extremely scientific I admit)

I blocked off about %60 of the grill with cardboard inserts and was planning to remove just enough to keep it from running too hot but it never went over 200 F with the AC blasting in 93 F heat up a 3 mile long mountain grade so I never ended up removing any. I also blocked off most anywhere air was still entering the grill could sneek around the radiator instead of thru it including the air going into the air dam openings. I made some cardboard triangles to go on the front of the mirrors and put some tape over the cracks around the headlights and stuff in the front. I also made some cardboard "air directors" underneath the truck to smooth airflow around a few of the biggest objects like frame pieces and such....

I was trying to just do stuff I was wiling to live with if it worked and I could make more permanent stuff but for all that work I gained about 2 MPH coasting down the 3 mile mountain VS before the aero mods and maybe 1/2 MPG if I round up a little on the 200 mile round trip I have been making 3 times a week. A couple aero things left I would like to try would be basically a full belly pan but have yet to find a suitable material, thinking about robbing some Prius belly pans at a JY because of the way the air extractor holes are made on them. I also have contemplated a temporary ramp reaching from the rear/top of the cab all the way down to the rear edge of the lowered tailgate but so far the only things I have come up with would be pretty heavy... would just be for experimenting anyhow as I use the bed a lot and need easy access. Other than that I will make some permanent grill inserts out of a black plastic tote and uncover just enough to keep things cool and ditch the cardboard underneath.

It is worth studying what GM found and patented about covering only about half of the open bed, strangely from tailgate forward:

https://patents.google.com/patent/US4573730A/en?oq=4573730

A professional aero guy would suggest that you should tape 5 inch long strings of yarn on the outside of the rear window, inside the bed, and across and down the tailgate. Then find someone else to coast your truck down the long hill while you video it. The video should show signs that you have a horizontal “whirlwind” behind the rear window, and a second whirlwind behind the tailgate. These whirlwinds “break loose” every so many seconds, followed by a new whirlwind forming. You want to make mods that “ lock the two whirlwinds into permanent attachment.” When the whirlwinds stay in place they create an “invisible sloping camper top” .

The V12 SRT Rams had blacked out front grille blockoff plates that removed at least half of the opening.

For your own education, coast down your hill with the mirrors folded flush against the side windows.

If you were a weird risk taking coal miner
you would coast down your hill with a tire air pressure 10% higher than max rating, but only on a dry day with nearly no traffic.

I did not know this until recently, but when I read Wheeler’s US Patent I found that he states that labeling tape with capital “V’s” impressed side by side function as tiny vortex generators. This might be an interesting experiment on mirror back edges, and perhaps where the glass windshield” meets the metal roof edge.

Why not try a deeper front air dam that is flexible, and perhaps a second, third or fourth dam placed underneath the truck, instead of an underpan.

Examine the “front spads” that some SUV’s have that block only half of the rear tire width.

I am now 90% convinced that a lot of the odd shaped rear brake light lens designs
are that shape to hold a whirlwind stable and attached.

With your junk yard connections could you get a add on overdrive unit to experiment with?

If you succeed at aero power reduction,
you need engine rpm reduction to get full benefit.

Just read about this new device:

https://www.cyclingweekly.com/revie...est-handlebar-mounted-wind-tunnel-so-far

but $900 is not “cheap” in my thinking,
even allowing that full vehicle size wind tunnel pricing is $500+ per hour

Just read about the aero of a Hyundai Ioniq 6 and the different tricks it uses to get the Cd down to 0.21

https://en.wikipedia.org/wiki/Hyundai_Ioniq_6

I might be worth looking one over carefully for potential aero mods to a pickup.

The replacement of “elephant ear’ outside mirrors
with thin aero shape video cameras
deserves some pondering

Depending upon your level of insanity, you may be interested in this HRD. Computer is set up for 18 to 1 AFR at part throttle cruise.

https://charlotte.craigslist.org/pts/d/concord-auto-chrysler-computer/7522075592.html

Saw a “Rivian” pickup charging at a Walmart last week.
I noticed that it did not have a front air dam, but did have front “half spads” covering the outside front third of the front tires.
Underbody was very smooth.
At the rear of the underside there was an upward slope creating a “diffuser” like Formula 1 car rears.
Had what appeared to be a factory tonneau of the roll up slat design.

I always wonder what all those well scienced out aromatics mods would do to ICE cars? They really have to stretch their imagination to squeeze every last bit of range out of those but never really apply that tech to real cars and trucks.

I stumbled across some really nice un-cracked magnum heads for this project so I will be porting them and milling them as much as possible... What do you guys think of sinking the valves in the magnum head a little so I can mill it more??? Would say .050 down hurt flow or anything? Seeing how the intake valve is the limiting factor for milling it more this would allow a little more milling to further reduce the chamber size and get some super size compression going in here. I could shim the springs or maybe run some LS chubby springs... what else am I missing with this idea?

I don't think I would sink the valve. I had small chamber W5 heads and they were the same with the valves very close to the deck. I had them shaved down to the seat so the intake valve actually set below the deck surface.

Thinking more on it this is probably what I will do then put a nick in the piston if I need it. Sinking the valves will in itself lower compression, going to be chasing very diminishing returns sinking valve and gaining a CC and then milling it to lower it 2 CC. I really wish I could find some drop in flat faced valves for these...

Coating the piston crowns and cylinder head chambers with a heat rejecting thermal ceramic coating would reduce the CC’s

The coating alone is also supposed to “approximately” improve fuel economy 3-4%

This technique is at least 20 years old.

I think some BMW M series have it.

sample quote

Thermal Barrier Piston Coatings

A Thermal Barrier Coating is a spray-on coating usually applied to the top surface of the piston. Its function is to reduce heat transfer into the top of the piston. The benefit of Thermal Barrier Coating is highly dependent on the application and its use. Thermal Barrier Coatings are more effective if other components of the engine such as the combustion chambers, valves, and exhaust system are also coated.

Advantages:

Thermal barrier coatings will reduce heat transfer from the combustion chamber to the piston crown.

Disadvantages:

There is some additional cost added to the price of the piston for adding a Thermal Barrier Coating. While the cost may be somewhat insignificant, there will be additional expenses in coating the other combustion components in order to yield the full benefits of Thermal Barrier Coating. Once the piston is coated, there cannot be any machining or modifications done to the piston crown. If any modifications are needed, the piston will need to be recoated.

Mahle offers its Powerpak piston kits which come with the Grafal coated piston skirts and a phosphate coating. These two coatings are mostly utilized for street and racing applications and have been proven reliable for many years. They are applied during the production process, so it is very inexpensive and well worth the benefits when the cost equates to pennies on the dollar. The other coatings are beneficial but are structured mainly for more specialized applications where engines are under severe and extreme conditions.

The benefits of piston coatings have been debated for many years, but if properly utilized in the right situations, they can be a great way to extend the internal part’s life expectancy and even the performance it delivers. If you think a particular coating might be better for your application or you are not sure which would yield the best results for your engine, give the folks at Mahle Motorsports a call and get the best recommendation from professionals.

end quote

https://www.chevyhardcore.com/tech-...s-when-you-should-and-shouldnt-use-them/

https://dsportmag.com/the-tech/education/quick-tech-thermal-barrier-coatings-for-more-power/

Coating the piston will not increase compression as it is already going to be as close as I dare to the head, with a film on it i will have to reduce piston to head distance the same amount. It would still have the thermal benifit but I would have to measure and make nachos in them before the coating, also if I get too close it will touch the head and possibly mess up the coating on the head and the piston...

Is there any good DIY kits that you know of?

I do not know of a DIY kit.

I would not sink the valves as you would be cutting through the hardening on the exhaust seats.

Just checked the Swain coatings sight they claim to have a piston coating that reduces octane requirement. I have an email in to them to find out more and will share what they tell me when I hear back.

Dave, do you have any ruined or unacceptably deep cracked Magnum cylinder heads?

I am just wondering whether there is enough metal around the factory spark plug hole threads to bore it out and re-thread for larger sparkplugs with deeper projected noses?

That would remove a few CC’s....

Check with Techlinecoatings.com they had diy products at one time, not sure if they still do

Check out my 2015 thread on
https://geometroforum.com/viewtopic.php?p=274701#p274701
CBC2 POWERKOTE heat coating
and Tech Line DFL-1 for bearings and cam

It still gets 52 mpg at 70 on a level highway.
28 years old and no one has made a more economical car since.

My 5.7 1997 RAM wagon gets 16 hwy at 70

This thread speaks directly to my desires for the engine I plan to use in my 56 Docge pickup daily driver. I'm mounting the 56 cab/box onto my 2001 2WD Dakota chassis, and ditching the 4.7/5-spd for a built 5.2 Magnum port EFI , as I like the idea of a classic Mopar engine in a vintage pickup. The drivetrain will be the 9.25" 3:55 ratio limited slip rear axle from my Dakota, overdrive trans of about .67 or .62 and stock tire diameter to get on highway revs at about 1800 at 75 mph. I know from many trips driving my 2001 Dakota if I can cruise at 60 mph in 5th gear (.72 ratio) it keeps the RPM just under 2000 and I have recorded fuel mileage over 21mpg. Based on that, with a built 5.2 EFI Magnum producing over 350 ft-lb of torque in the 1600 to 2000 rpm range, I feel its possible to achive consistent 20mpg at 75 mph, and still enjoy over 350 rwhp when I want to stomp on it.

Gene has a 318 in his vintage pickup on a Dakota chassis and said he's gotten 20mpg on occassion. Thanks to Gene's suggestions I ditched the plans for a 4.7HO and will go with the classic build plans for a 5.2 Magnum EFI, Keith Black flat top pistons, deck the block, 5.9 heads, block hugger headers/dual Magnaflo exhaust, Edlebrock Air Gap intake manifold, MSD ignition and whatever else I can plan to create a vintage daily driver that can produce good fuel mileage for highway cruising.

Couple points for consideration. 5.2 and 5.9 magnum heads are the same, no difference so use whatever good set you have or can find.

If you are going to deck the block, you may not need to spend money for KB pistons as 5.2 pistons are closer to the deck than 5.9. If bores are good just deck the block to get the piston crown to zero deck or close.

Magnum manifolds would be fine if they fit and there would be very little if any improvement with block hugger headers. A regular performer intake manifold with a thermoquad( or second choice quadrajet) will net you the best mileage if you are switching over to carb.

Maybe be overkill, but if you are going all out on mileage an 8.25 rear would be worth a little over the 9.25. Tonneau cover and electric fan are also worth looking at.

I took the heads for this project to the machine shop yesterday to get a 3 angle valve job and milled and they said it would be over $500 or about double what I paid a year ago for a similar job on a customers heads and I had already hot tanked them and cleaned em up, I always used em because they were convenient their work was never great machine work anyhow so I brought em back home with me and am looking for a different machine shop.

Been reading this from the start and now ready to get er done. My plan, 92 360 with the lock up overdrive (ditching the 904) SP2P intake TQ or QJ, heads off the 88 318. I’m sending the cam out to get reground but can’t remember the specs recommended, lost in the back posts, so ?? Anything else? 88 150 pickup 2x

It's getting to the point where it's cheaper, for my 230 flathead anyway, to just buy the tools and do a three angle VJ myself.

Correct, I bought a Quic Way valve grinder and Van Norman seat machine 3 years ago for $1100

Since I don't already have a 5.2 Magnum to start with, I'm shopping for whatever I can get to make the best daily driver 318. I'm leaning toward port fuel injection for the better fuel mileage. So what year 5.2 Magnum should I shop to buy? Seems that anything 5.2 Magnum after 1995 is a good choice, correct? I may use the Mopar factory performance heads or go for a set of aluminum aftermarket heads with the bigger valves. I have a decent budget so I can select the best cam for torquey power, best Edlebrock EFI intake and a good set of headers.

TBI does better MPG because the fuel has more time to vapoorize. My TBI 318 dakota got significantly better MPG than this one or any stock magnum engine truck I have ever owned. Now they are not great on power but that is a different question...

I had thought about doing something like this using a 273 or a 318 with a ported SP2P manifold and a small hydraulic roller with the small chamber "302" heads and fariy high compression. I was going to use a OD 833 with the goal of well over 30mpg highway.

I had a 94 Firehark with an LT1 and a 6 speed and that sucker would run 13's all night long and get 31 mpg on the way home. the .29 drag coefficient and the motor turning under 1500 RPM at 60mph made a huge difference. part throttle torque at low rpm and aerodymanics really make a difference. EX the 1960's VW bug had the same chassis and engine as the Karmen Ghia but the KG got something like 30% better highway MPG.

it's very doable

What’s the lowest gear the 8-1/4 came with? I’m thinking now of still keeping the 904 with hat low first gear instead of an overdrive behind the 360. Also keeping the TBI adapting to the SP intake with 318 heads.

The lowest gear I have seen in a factory 8.25 is 3.92 however I think you are actually wanting to know the highest gear and the highest I have seen is a 2.20 with a 2.45 being fairly common.

Yes highest, but I do have a 4.30 posi in a A-body rear size

The higher number of gear makes it a lower gear rear end. A 4:10 is a low gear, but a 2:76 is a high gear. Sounds pretty dumb, but that is how it works. Its easier to picture the speed at a given rpm. With 4:10 gears at 2,000 rpm, the vehicle speed will be pretty low. But with 2:76 gears at the same 2,000 rpm, the vehicle speed is much higher.

I had a 2:76 gear 8 1/4 in a 54 Dodge pickup for a while. The problem with that high of a gear is that you put your foot into the gas pedal more to get it to crawl away from stop signs. That gear with tall 15" tires sure kills off the stop power. I actually gained about 2 mpg when I swapped in a 3:23 geared 8 3/4 into the truck. I didn't have to step into the gas so hard to get the truck to move.

The OD with the lower gear is the best of both worlds, you get it rolling easier with less throttle input the lower gear, than once at a steady cruising speed on the highway, the OD drops the rpm. Those small block Mopars are very efficient at 1800 -2000 rpm at the chosen mph. Gear the rear end to turn those 1800-2000 rpms at the speed you expect to be driving at the most. Much lower rpm and it works too hard pulling hills of any height and will kill the mpg. Its very hard to find a cam that will produce the torque you need to pull the hills at those low rpms.

It's not dumb at all... the higher your transmission gear the faster you go, the higher your rear end gear the faster you go. Lower trans gears are for lower speeds and lower rear end gears are for lower speeds.

Confusion abounds in “gear ratio” as regards good fuel economy.

I suggest talking about MPH for each 1000 rpm, which takes everything into consideration, including tire diameter.

As regards getting the “right camshaft grind” for fuel economy, that is especially tough.
Today “variable valve timing” certainly improves late model engine fuel efficiency
but adjusting “ground in camshaft values”
down to what VVT is truly doing to the valves in today’s “real world”
is nearly impossible because even today’s 1800 page FSM
does not have tables about what modern PCM software commands are making happen to lift and duration.

There is another 10% fuel economy improvement if the air to fuel ratio goes from 14.7 to 18 or more.

There is an old Autospeed.com article about the early year Australia spec Honda Insight
and how at steady cruise speed on a level highway its air to fuel ratio would lean out to 25 to 1.

The A500/42RH also comes with the 2.77 first gear ratio.

Factory roller cam in '85+ 2bbl 318 cars. Off idle torque through about 4500 RPM. I think those motors were rated at 230 ft/lbs and 150HP.

It does not work harder at lower RPM, it does the exact same amount of work as long as it is able to maintain speed without downshifting. Back when everyone ran carbs and it was harder to atomize fuel properly at very low RPM and high load an engine could get worse MPG if the RPM were too low because the fuel simply wasn't able to burn fast enough before the piston was at BDC and the ex valve opened, modern engine/trans combos really bring the RPM down at high speeds and have picked up quite a bit of MPG by doing so. At low RPM and high load is when an engine should get best MPG if everything is ideal.

I like to think in terms of "displacement per mile" for example a 400 CID engine with a 2.28 gear ratio would have the same displacement per mile as a 200 CID with 4.56 gear ratio (tire diameter and such all being equal). They would have roughly the same performance all else being equal and in this case neither would be quick off the line but both should run satisfactorily at cruising speeds. If both engines were of the same design they would both have roughly equal air volume and speed in the ports. The 400 CID engine turning 1500 revolutions per mile would inhale the same air as the 200 CID engine turning 3000 revolutions per mile.

My opening point was, many new to the automotive world, or those that have not been taught better, believe that a rear end gear in the 4:00 something (4:10, 4:88) is a high rear end gear (big numbers) and that a rear end gear in the 2:00 something (2:45 or 2:76) is a low rear end gear (low numbers) when in fact both of these statements are incorrect. A 4:00 something rear end gear is considered a low gear ratio and a 2:00 something rear end gear is considered a high rear end gear. We need to be sure people learn these things correctly, and if they don't hear it from us, who would they hear it from?

If you are cruising along in your ride at 1800 rpm at 70 mph, and you come to a 5% grade increase on the road, to maintain the 70 mph speed, you have to open the throttle. How much, and for how long you open that throttle for will depend on the torque the motor has. As soon as you open that throttle more then it was opened before the 5% grade, you are reducing the fuel mileage the motor is getting. In the over all picture a one time event probably will not make much difference, but should it happen often, the throttle effect will have more impact on the mpg.

The point someone brought up about the mid 80s 318 2bbl wit the OD and the 2:71 rear gear was interesting. If you actually drove any of those vehicles you fully understand what I am talking about. Even the slightest increase in the grade on the highway would drop the trans out of OD. If the vehicle was running on cruise control, after it dropped out of OD, it would also unlock the converter, and if the hill was big or long enough, it would open the throttle wide open, and might even shift the trans into "passing" gear. I worked at Chrysler as a tech from 86-88. Guess what the biggest complaints about those new OD transmissions were? Constantly engaging and disengaging the OD on hilly country roads. If they were driven and used on pretty level roads, they pulled some pretty good mpg, but throw in a few hills, and that mpg dropped. Chrysler actually limited the availability of getting the high rear gear and the OD in some locations across the country

I agree with this, in fact I reprogrammed my transmission in one of my vehicles where it won't even go into OD below about 47MPH because the factory OD would be annoyingly kicking in and out between 25 and 45 just cruising around town.

And guess what? the city MPG picked up!

I think I'd rather use the deep first and second gear 904 and gear the rear for whatever you think is going to be the most efficient highway rpm (+/- 200 rpm) at whatever speed you real-world plan to drive....70? 75?

EX: The low gear 904 (2.74:1) turns a 4.10 into an effective 4.56 rear for launching compared to the standard (2.45:1) in terms of torque multiplication.

Nobody ever drove an old 318 2bbl with OD and 2.71 rear end that was stock. They never used the automatic OD with a carb, and the old carb engines were insanely crippled by the emissions equipment of that era so not really relative and they also never used an OD trans with a 2.71 rear gear, 3.21 is the highest gear they used behind the automatic OD and that was in the dakota with a pretty short tire otherwise 3.55 was as high as it went... mine has the 3.55 and it is turning way too many RPM for max MPG on the open road even in OD and LU and in fact gets worse MPG than my 3/4 ton 4x4 4 door long bed with a 6.4 did.

I previously had a 1999 318 NV 3500 4x4 dakota with much taller tires and I could leave it in 5th gear almost exclusively except initial acceleration and it would motor right along even 35 MPH and at highway speeds it would not lose speed up even decent sized hills with lugging it and it would almost always give me near 20 MPG city or highway, that excesive down shifting is just that, excessive downshifting and is the reason I hate automatics, they downshift way more than needed for normal cruising no reason an engine like a 318 magnum can't pull a 2.76 gear with short tires in a light vehicle and stay in OD most of the time.

Having owned a 260 cubic inch V8 that was great fun in a light car with a small frontal area to push through the wind,
I wonder whether 318 or 273 is “too big”.

I like V8s.
They are rare but I also like Flat 6 engines too.

Indeed a 4:10 is a high numeric ratio while also being a low gear in application and 2:76 is a low numeric ratio while also being a high gear in application.

I been thinking about buying a valve grinder off craigslist for around $500, I keep seeing them pop up on there. As for the seats I keep watching videos of these type things...


https://www.youtube.com/watch?v=F03KOZYDIc8

I am just concerned with how do I control depth and valve seat diameters and such? Seems he is just guessing that it is close...

The Van Norman has precise cut measurements, not a guess.

some of the very old machines had an adjustable collar type stop that had a tendency to slip, but the van norman machines have a positive stop that is very accurate, as it doesn't slip after setting.